Converted to PLO a year back and will never go back to NLH unless I'm playing a big GTD live or online tournament. It's such a great game with a way better dynamic IMO. I play mostly on Global Poker now and the games are awesome, and the volume on the PLO tables go up week after week. Lots of 2/4 and 3/6 action and higher if you want it! The boom is coming... Limit Hold Em was the big game forever and then NL took off. Things change eventually!
There was a PLO boom when it was getting more popular; no reason to think it will boom again. If one plays both, it makes little difference. But I would stick to NLH if I were a new player and then see later if one wants to play PLO also.
Thinking one picks PLO when one suddenly happens to like it and there are good games now, means mostly that one will end up playing both in the long run.
I could see a bit of a boom when a good amount of US states segregate player pools and there is a larger online player pool. In 10 years maybe we can see this. As of now gubberments have screwed everything up.